The estimates of fur seal consumption of krill in subareas 48.1 to 48.3 which have been used in ecosystem modelling and CCAMLR’s risk assessment approach, are based on the distribution of fur seal breeding populations. Fur seal breeding colonies south of 60o have remained relatively small and their biomass is orders of magnitude less than those of penguins. As a result the estimates of fur seal consumption outside of the South Georgia region, where ~95% of the population breeds, are relatively insignificant. However evidence from the growing body of tracking data has revealed the importance of the South Orkneys and Peninsula regions to male fur seals during their post mating dispersal from breeding sites on South Georgia. Using a combination of published and BAS data we highlight the potential importance of this connectivity. Our estimates suggest that the influx of fur seal males from South Georgia has a significant impact on the marine environment around the South Orkney Islands with a potential total krill consumption of approximately 86,500 tonnes. This is very likely an underestimate as it is based on a census of the fur seal population at South Georgia from 1991 which represented a year of poor environmental conditions. This population has also undoubtedly grown since this count. Our estimates also do not account for the need of male fur seals to recover condition during this time after fasting during the mating season and a number of important data gaps exist. We recommend further detailed analysis is prioritised in order to provide more robust estimates of the fur seal impact on this region that can be used to inform management, including through the risk assessment framework.
Dr Simeon Hill (United Kingdom)
Dr Chris Darby (United Kingdom)